A computer system has at least two processing nodes and a shared data storage system comprising a number of storage units. Each storage unit has a logical unit number (LUN). A first of the processing nodes stores a maximum LUN value in non-volatile storage, and is arranged to perform, on boot-up, a device discovery procedure in which it scans the shared data storage system to find storage units with LUNs not greater than the maximum LUN value. A second of the processing nodes stores a start LUN value in non-volatile storage, and is arranged to perform, on boot-up, a device discovery procedure in which it scans the shared data storage system to find storage units with LUNs not less than the start LUN value. This allows LUN masking to be achieved relatively inexpensively with only minimal modification to the operating systems of the processing nodes, using existing device discovery features of the operating system.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of masking logical unit numbers (LUNs) comprising the steps: storing a first parameter in non-volatile storage in a first processing node, said first parameter defining a first range of LUN values; storing a second parameter in non-volatile storage in a second processing node, said second parameter defining a second range of LUN values, non-overlapping with said first range of LUN values; causing the first processing to perform, on boot-up, a device discovery procedure which scans a shared data system to find storage units with LUNs in said first range of LUN values; and causing the second processing node to perform, on boot-up, a device discovery procedure which scans the shared data storage system to find storage units with LUNs in said second range of LUN values.
2. A method according to claim 1 wherein: said first parameter defines a maximum LUN value; said first range of LUN values comprises LUN values not greater than said maximum LUN value; said second parameter defines a start LUN value; and said second range of LUN values comprises LUN values not less than said start LUN value.
3. A method according to claim 2 wherein the device discovery procedure in the second of the processing nodes scans the shared data storage system to find storage units with LUNs in a range between the start LUN value and the start LUN value plus a predetermined constant value.
4. A according to claim 2 wherein the second of the processing nodes also stores a stop LUN value in non-volatile storage, and wherein the device discovery procedure in the second of the processing nodes scans the shared data storage system to find storage units with LUNs in a rang between the start LUN value and the stop LUN value.
5. A method according claim 1 wherein the processing nodes are connected to the data storage system by way of Fibre Channel connection, using the SCSI protocol.
6. A computer system comprising: at least two processing nodes; and a shared data storage system comprising a plurality of storage units, each having a logical unit number (LUN) associated with it; wherein a first of the processing nodes stores a first parameter in non-volatile storage, said first parameter defining a first range of LUN values, and includes means for performing, on boot-up, a device discovery procedure which scans the shared data storage to find storage units with LUNs in said first range of LUN values; and wherein a second of the processing nodes stores a second parameter in non-volatile storage, said second parameter defining a second range of LUN values, non-overlapping with said first range of LUN values, and includes means for performing, on boot-up, a device discovery procedure which scans the shared data storage system to find storage units with LUNs in said second range of LUN values.
7. A computer system according to claim 6 wherein: said first parameter defines a maximum LUN value; said first range of LUN comprises LUN values not greater than said maximum LUN value; said second parameter defines a start LUN value; and said second range of LUN values comprises LUN values not less than said start LUN value.
8. A computer system according to claim 7 wherein the second of the processing nodes includes means or scanning the shared data storage system to find storage units with LUNs in a range between the start LUN value and the start LUN value plus a predetermined constant value.
9. A computer system according to claim 7 wherein the second of the processing nodes also stores a stop LUN value in non-volatile storage, and wherein the second of the processing nodes includes means for scanning the shared data storage system to find storage units with LUNs in a range between the start LUN value and the stop LUN value.
10. A computer system according to claim 6 wherein the processing nodes are connected to the data stomp by way of a Fibre Channel connection, using the SCSI protocol.
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January 11, 2001
July 13, 2004
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